04spring注解

注解功能
1）配置spring容器
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.3.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.3.xsd">

<context:annotation-config/>
<context:component-scan base-package="com.fz.entity"/>
</beans>
2)注解使用
@Component 如果不写，则使用类名小写作为名称

@Component("uuu")

@Data @Component
public class Book {
@Value("100")
private int id;

@Value("《mysql数据库技术》")
private String name;
}

@Autowired 根据类型自动装配

@Autowired //根据类型自动装配 byType

@Autowired @Qualifier("user") //根据名称自动装配 byName
private User user;

@Resource(name="book")

3)注解bean类方法
注解bean类 com.entity.Db类
---------------------------------------------------
@Component("db")
public class Db {
public void show(){
System.out.println("dbshow");
}
}

@Controller("member")
public class Member {
public void save(){
System.out.println("saveok");
}
}

@Service("m")
public class Member {
public void save(){
System.out.println("saveok");
}
}

@Repository("mm")
public class Member {
public void save(){
System.out.println("saveok");
}
}
4)注解单例 多例
---------------------------------------------------
@Repository("mm") @Scope("singleton") 单例默认
public class Member {

}

@Repository("mm") @Scope("prototype") 多实例
public class Member {

}

5）注解初始化方法
import javax.annotation.PostConstruct;
---------------------------------------------------
@PostConstruct
public void a(){
System.out.println("初始化1");
}

@PostConstruct
public void init(){
System.out.println("初始化2");
}

6）注解销毁方法
import javax.annotation.PreDestroy;
---------------------------------------------------
@PreDestroy
public void close(){
System.out.println("退出");
}

@PreDestroy
public void exit(){
System.out.println("销毁");
}

7)属性注入
-------------------------------------------------------
@Data
@Component("book")
@Scope("prototype")
public class Book {
@Value("BS101")
private String bid;
@Value("java书籍")
private String bname;
}

@Data @Repository("mm") @Scope("prototype")
public class Member {
@Resource(name="book") 此处的book 就是指定工厂中的 上的那book名@Component("book")
相当于beans.xml 中的<property name="" ref="u"></property>
private Book book;

}

@Data @Repository("mm") @Scope("prototype")
public class Member {
@Autowired 根据类型自动注入对象
private Book book;
}

8）延迟加载
-----------------------------------------------------------------
单例模式是默认的，会立即加载 加上@Lazy 不自动加载，第一次使用时再加载
@Data
@Component @Scope("singletone") @Lazy
public class Teacher {
private String name;

public Teacher() {
System.out.println("空构造方法");
}

public Teacher(String name) {
this.name = name;
System.out.println("有参数name的构造方法");
}
public void info(){
System.out.println("老师姓名："+this.name);
}
}

@Scope("prototype") 多实例，默认使用的使用时加载

@Data @Repository("mm") @Scope("singleton") @Lazy 延迟加载，在第一次使用时加载
public class Member {

}

@Data @Repository("mm") @Scope("singleton") @Lazy(false) 立即加载初始化
public class Member {
}

beans.xml

<beans default-lazy-init="true"> 所有bean都延迟实例化初始化加载

<beans default-autowire="byName">默认注入相关属性对象